Abstract：Objective: To investigate the protective effect and molecular mechanism of amygdalin on hyperglucose-induced injury in human retinal endothelial cells (HRECs) through regulation of the cGAS-STING pathway. Methods: An HREC injury model was established using 33 mM high glucose induction. The model was validated through CCK-8 assay, Annexin V/PI double staining, transmission electron microscopy, and ROS level detection to assess cell proliferation, apoptosis, mitochondrial morphology, and intracellular ROS levels. HRECs were treated with 100μM amygdalin to intervene in hyperglucose-induced injury. Changes in cell survival, IFN-α secretion, and cGAS/STING mRNA expression were detected using Annexin V/PI double staining, ELISA, and RT-qPCR. Subsequently, the STING inhibitor C176 (2μM) and cGAS agonist RU.521 (10μM) were applied, and the signaling pathway affected by amygdalin was examined through RT-qPCR, immunofluorescence, Western blot, and Transwell assays. The cGAS gene was knocked down using siRNA, and the alternative TLR4/MyD88 pathway was excluded using the TLR4 inhibitor TAK-242. Results: Treatment with 33 mM high glucose for 48 hours reduced cell viability, increased apoptosis, induced mitochondrial damage, elevated ROS levels, upregulated Cleaved caspase-3 expression, and increased the Bax/Bcl-2 protein expression ratio (all P<0.05). Treatment with 100μM amygdalin significantly improved cell survival, restored LDH levels, upregulated cGAS/STING mRNA expression, promoted STING Golgi translocation, and enhanced IFN-α secretion (all P<0.05). Amygdalin activated the cGAS-STING pathway, leading to increased cell viability, elevated p-TBK1/p-IRF3 expression, and reduced apoptosis -- effects that were reversed by C176 (all P<0.05). Functional recovery experiments showed that amygdalin restored trans-epithelial electrical resistance (TEER) values, increased cell junction density, reduced secretion of inflammatory factors IL-6 and TNF-α, and decreased NO levels (all P<0.05). Knocking down cGAS with siRNA increased apoptosis and SA-β-gal positivity again, while no significant changes were observed in TLR4 pathway-related indicators. Conclusion: Amygdalin specifically activates the cGAS-STING pathway, inhibits mitochondrial damage and DNA breakage, and reduces inflammatory responses, thereby ameliorating high glucose-induced injury in retinal endothelial cells. This effect is independent of the TLR4/MyD88 signaling axis, providing a new therapeutic target for diabetic retinopathy.
2025, Vol. 31 
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